Installation for the treatment of minerals on a continuous grate

ABSTRACT

An installation for the hot gaseous-flow treatment of pelletized minerals, employing a straight-line or circular continuous grate or chain formed by a series of cars and mechanisms for driving the cars and comprising a charging zone, at least one treatment station in each of which the grate passes between fixed gastight hoods, one upper and one lower, a discharge zone and if necessary neutral zones or cooling zones, the car frames being water cooled and lateral gas seals being provided between the cars and the upper and lower hoods, the lateral seals being water troughs into which the side walls of the cars dip.

United States Patent 1191 3,907,262

Bonnaure Sept. 23, 1975 [54] INSTALLATION FOR THE TREATMENT OF 3,559,967 2/1971 Werner 432/245 MINERALS ON A CONTINUOUS GRATE 3,589,691 6/1971 Greaves 266/21 X 3,614,076 10/1971 Schmidt et al.. 266/21 Inventor: Edouard Bonnaure, Le Vesinet, 3,761,359 9/1973 Von Hippel 266 20 x France FOREIGN PATENTS OR APPLICATIONS [731 Assignee: creusm'uire Entrepfises Paris 78,630 7/1970 Germany 432/137 France 1,922,065 11/1970 Germany 432/137 [22] Filed: Apr. 9, 1973 Primary ExaminerGranville Y. Custer, Jr. [21] Appl' 349044 Assistant Examiner-Paul A. Bell Attorney, Agent, or Firm-Cameron, Kerkam, Sutton, [30] Foreign Application Priority Data Stowe & Stowe Feb. 17, 1972 France 72.17621 [57] ABSTRACT U-S. CI. An installation for the hot gaseous-flow treatment of [5 II."- Clpelletized minerals employing a straight line or cirou- Fleld of Search lar continuous grate or chain formed a eries of 432/137, 160, 142, 144, 242, 243, 244, cars and mechanisms for driving the cars and compris- 139, 7, 17 ing a charging zone, at least one treatment station in each of which the grate passes between fixed gastight 7 References Cited hoods, one upper and one lower, a discharge zone and UNITED STATES PATENTS if necessary neutral zones or cooling zones, the car 2,977,106 3/1961 Duff 432/243 X frames being Water cooled and lateral gas Seals being N 432 137 X provided between the cars and the upper and lower 266/21 X hoods, the lateral 'seals being water troughs into which 3,367,644 2/1968 Ban 266/21 X the side walls of the cars dip.

3,460,818 8/1969 Greaves et a1. 266/21 3,536,307 10/1970 Hess 266/21 x 4 Claims, 9 Drawing Figures 3,172,936 3/1965 Koontz.. 3,302,936 2/1967 Ban US Patent Sept. 23,1975 Sheet 3 of5 3,907,262

US Patent Sept. 23,1975 Sheet4 of5 3,907,262

Sept. 23,1975 Sheet 5 of 5 US Patent FIG=9 INSTALLATION FOR THE TREATMENT OF MINERALS ON A CONTINUOUS GRATE The present invention refers to an installation for the hot gaseous-flow treatment of pelletized minerals, employing a continuous chain or grate. It is applied more particularly, by way of example, to the putting into effect of the reduction of ferrous minerals by hydrogen in order to produce deoxidized solid products such as sponge-iron.

In such an installation for the treatment of minerals on a continuous chain, the cars composing the chain pass in succession through Zones having various functions; generally the zones for treatment by passing through a gas flow are the largest and hottest, that is to say, the cars there undergo considerable thermal strains of long duration, injurious to their good upkeep. On the other hand the gases employed for treatment of the mineral are generally costly and it is important to limit leakages between the gas inlet and exhaust hoods and the cars bearing the mineral.

According to the present invention there is provided an installation for the hot gaseous-flow treatment of pelletized minerals, employing a straight-line or circular continuous grate or chain formed by a series of cars and mechanisms for driving the cars and comprising a charging zone, at least one treatment station in each of which the grate passes between fixed gastight hoods, one upper and one lower, a discharge zone and if necessary neutral zones or cooling zones, the frames of the cars including water cooling circuit means and lateral gastight sealing means being provided between the movable cars and the fixed upper and lower hoods, said sealing means including water seals arranged outside the gas flow path, the cars bearing blades which rotate with them and dip into fixed troughs filled with water and closed at their ends by flexible lips enabling the car blades to pass through.

The invention will now be described in greater detail by referring to a particular embodiment given by way of example and displayed in the attached drawings.

FIG. 1 gives a diagrammatic plan view of an installation in accordance with the invention in the case where a continuous circular chain. is employed for the reduction of minerals by a flow of hydrogen;

FIG. 2 is a more detailed section of the installation along IIII in FIG. 1, in a reduction zone;

FIG. 3 is a view from above of the cooled frame of a car;

FIG. 4 is a section along lV-IV in FIG. 3, showing in addition the grate bars of the car and the transverse gas-tight sealing between two successive cars;

FIG. 5 displays diagrammatically the tilting of the cars in the discharge Zone;

FIGS. 6 and 7 display the detail of the lateral gastight sealing between the cars and the hoods in the treatment zones. FIG. 6 reproduces on a larger scale a portion of FIG. 2, FIG. 7 is a section along VIIVII in FIG. 6, restricted to the two ends of a treatment zone;

FIG. 8 displays in a simplified way the apparatus enabling the laying of transverse gas-tight seals between successive cars, and

FIG. 9 is a partial axial section along IXIX in FIG. I, in a neutral zone.

Referring to FIG. I, the horizontal circular grate moves in the direction indicated by the arrow 1. At 2 takes place the laying of the transverse gas-tight sealing between cars as will be detailed below. At 3 the grate protection and the green pellets enter. Predrying and drying take place at 4 and 5 and firing at 6. At 7 a neutral zone is shown. Reduction is carried out at 8, 9 and 10. The neutral zone 11 precedes the cooling zone 12, followed by a third neutral zone 13. At 14 occurs the tilting of the cars, discharge of the products and return of the cars to the horizontal.

Movement of the cars on their rails is ensured in two distinct ways, namely:

in zones 2 to 13 inclusive, the drive is effected so that the grate cars move remaining contiguous,

in zone 14, on the contrary, the cars are driven individually so as to be no longer contiguous and to be able to tilt without difficulty as will be explained below.

A synchronizing device between the zones 2 to 13 on the one hand and 14 on the other hand enables the whole of the grate to be speeded up or slowed down.

In FIG. 1 are displayed the inlets for the grate protection at 15 and the green pellets at 16. The assembly 17 comprises the dust-extractors, fans, combustion chambers and stacks corresponding with the zones 4, 5 and 6. The conditioner units for the reducing gas are fixed at l8, l9 and 20. The exchangers, fans and dustextractors connected with the cooling zone 12 are installed at 21.

The products discharged at 14 are taken away by conveyors 22 towards the sorter unit 23 and the compactor-briquetter unit 24.

The car cooling-water admission can be effected via the axis 25 of the chain. At 26 is represented a feedpipe to one of the cars.

The car can also be fed with water by siphon from a circular trough installed along the chain as indicated in FIG. 2.

A car maintenance crane 27 is installed above the zones 14 and 2.

FIG. 1 does not display storage and homogenisation bays drying, crushing and green pelletizing installations or reducing and neutral gas production units, the positioning of which relative to the grate itself is relatively unimportant,

Referring now to FIG. 2, the hot dry reducing gas enters through the fabricated pipe 28 which is clad internally with an insulating refractory coating.

The upper hood 29, likewise fabricated and clad is hung by ties 30 from an upper girder system 31.

The fabricated boxes 32 are connected to hood 29 and are cooled by water circulation. Boxes 29 are protected on the inside next to the hood by an insulating layer. Boxes 32 support the coating and protect from the hot gases the upper portions of the raised sides 33 of the cars as well as the lateral water-seals 34 also known as lateral water-guards.

The upper water-guards 34 intended to ensure lateral gastightness are fastened to the hood 29 and the fabricated boxes 32.

The fabricated boxes and the upper water-guards are arranged all round the chain in contiguous members of medium dimensions (1 to 2 meters), joined together by bolting or rivetting.

Water feed to boxes 32 is effected individually. The water-guards are furnished with water inlets and outlets arranged so as to ensure on the one hand the water gauge balancing the pressure inside the hood without leakage of the reducing gas and on the other hand a flow of water maintaining the temperature of this water at a suitable level and compensating the leakage at the ends of the water seals as will be mentioned later.

The cars are essentially composed of a fabricated or cast frame 35, having an internal water-circulation. bolted on to stringers 36 which carry the two outer rollers 37 and the two inner rollers 38. The frame carries the grate bars 39, the raised sides 33 being bolted on to the stringers, as well as the lower plates 40 for the gas-tight sealing.

The rollers run on four concentric rails 41 and 42. The outer rails 41 remain horizontal round their whole circumference, but the inner rails 42 drop in the zone 14 to enable emptying of the cars as may be seen in FIG. 5.

Movement in the zones 2 to 13 inclusive in FIG. 1 may be imparted to the cars in various ways, for example by bearing mechanically against the axles 43 extending the outer rollers from the cars 37, the bearing devices being of chain, rake, friction or other type. It may be useful to arrange them at a number of points on the outer and inner edges of the chain, functioning in a synchronous manner.

The fabricated frames are conveniently fed with water by siphon from an upper trough 44 parallel with the chain. The upper water intakes 45 are supported by a chain 46 endowed with movement parallel with that of the main grate. A flexible tubing 47 ensures the connection with the water inlet 48 to the frame so as to limit the movements of the inlet orifice in the tilting zone 14.

The water outlet 49 opens into a trough 50 parallel with the lower water-guards 51.

The gases which has passed through the layer of material are collected in the lower hood 52 from which the connecting pipe 53 leaves in the direction of the corresponding conditioner unit. Dust is recovered by change of direction and removed by the continuously-acting device 54. In the zone 14 the movement of the chain may be ensured by bearing against the axles 43 by chains or rakes furnished with hook fingers having a pitch greater than the length of the cars and moving at variable speed, some of the time higher than and some of the time equal to the speed in the zones 2 to 13 so as to obtain between cars sufficient clearance for the tilting and at the beginning and end of the zone 14 speeds equal to the speed of the chain in the zones 2 to 13.

Referring to FIGS. 3 and 4, the bars 39 of the grate rest on the cooled cross-members of the frame. They are contiguous and the passages between them are set by suitable bosses machined or cast in. Lugs 55 ensure support on the cross-members of the frame and on the other hand a transverse rod 56 guarantees the security of the connection between the bars and between them and the stringers 36. The slant to about 45 during tilting in fact enables much simpler attachment of the bars to the frame than in the case of a straightline chain in which the cars are turned completely over along the return side.

In FIG. it will be observed that in the tilting zone the rails 41 furthest out remain horizontal, whereas the inner rails42 curve downwards. This tilting movement combined with a horizontal displacement as described at the end of paragraph 2 enables emptying the car loads into a bottom exhaust hopper.

The grate-bearing frame can il'necessary be clad with a layer 57 (FIG. 4) made of insulating and inert materials limiting thermal losses and gas-to-metal contacts.

According to FIGS. 6 and 7 the raised side-s 33 of the cars, also known as the sidewalls, are furnished with an outer vertical wall 58 dipping into the upper waterguard 34. At the start and the finish of the water-guards the water is held in by rubber membranes 59 and 60 which bear against the vertical movable walls 58. A number of membrane assemblies may be arranged in succession in order to reduce the water losses at the ends. The same system is adaptable to the lower waterguards 51.

FIG. 8 displays an embodiment of the transverse gastight sealing between two successive cars, as may be put in position in zone 2, that is to say, before loading material on to the grate.

The edges of the top ends of the raised sides 33, their horizontal fiat portions and dipping walls 58, as well as those of the end cross-beams of the frame 35 are furnished with a continuous half-throat 61 (FIG. 4) extended if necessary by a little rim 62, cast-in or machined. The throat created by the coming together of two continuous cars will be packed with a metalloplastic cord or, better, will be filled with a special refractory cement projected by compressed-air pistols 63 effecting a guniting in beads. The pistols move transversely on a movable beam 64 which follows the movement of the grate at the same speed as the latter. The assembly then runs back to effect the sealing of the next join between the cars. One can imagine two series of pistols, one projecting, for example, an adhesive cement, the other a sealing cement.

During emptying of the cars in 14 the cement will be destroyed and exhausted with the other products. At the entrance to zone 2 the throats will be cleaned auto matically before the new application of gastight joints.

The same device can be applied underneath the cars.

FIG. 9 displays an embodiment of the neutral zones 7 and 11.

The vault 65 of the neutral zone is lower than those of the other zones. It extends over a length greater than that of a car. It is closed at the ends by two vertical dampers 66 which may have water circulation and are adjustable in height so as to limit to the minimum the free section above the layer of materials.

The vault is pierced with holes enabling the admission of a cold neutral gas at a pressure very slightly higher than that obtaining in the adjoining hoods 68 and 69, so that the neutral gas flows very slightly towards the hoods 68 and 69 and not the opposite.

Underneath the cars a box 70 of the same dimensions as the vault 65 is applied under controlled pressure against the machined bottom of the frames 35. The box 70 is hollow and furnished in its upper face with an array of holes 71 which enable the admission of neutral gas at a pressure very slightly higher than that in the lower hoods 72 and 73 and hence a leakage flow adjusted to a minimum in the direction of these hoods.

Closures are applied at the level of the water seals which are located outside the flow of hot gases similar in action to dampers 66, and are water-cooled diaphragms which limit the free passages to a minimum.

The leakage flows of neutral gas are in every case relatively small because the pressures in the hoods to be separated are themselves very nearly the same. The case is a little different with the neutral zone 13 which may usefully be composed of two contiguous neutral zones, the first neutral zone located near the cooling zone 12 being a neutral gas zone, the second being an air circulation zone inasmuch as a considerable leakage flow towards atmosphere will have to be tolerated and air costs nothing.

Of course the invention is not strictly limited to the single embodiment which has just been described by way of example, but it also covers every variant 1 claim:

1. An installation for the hot gaseous-flow treatment of pelletized minerals, employing a circular continuous grate formed by a series of cars and mechanisms for driving the cars and comprising a charging zone, at least one treatment station in each of which the grate passes between fixed gastight hoods, one upper and one lower, a discharge zone and neutral zones and cooling zones, the frames of the cars including water cooling circuit means and lateral gastight sealing means between the movable cars and the fixed upper and lower hoods, said sealing means including water seals arranged outside the gas flow path, the cars carrying blades which move with them and dip into fixed troughs filled with water and closed at their ends by flexible lips enabling the car blades to pass through, the cars and their grate-supporting cross-beams being clad with an inert insulating refractory layer and means for providing gastight sealing between two successive cars before approach to the charging station.

2. An installation for treatment as in claim 1, wherein said means for transverse gastight sealing include projection of a plastic refractory cement into the space transversely separating two successive cars.

3. An installation for treatment as in claim 1, wherein said means for transverse gastight sealing include a metalloplastic cord in the space transversely separating two successive cars.

4. An installation for treatment as in claim 1, comprising neutral zones between different active zones, in each neutral zone and in the portion located above the cars the vault being lowered and closed at each end of the zone by a transverse damper adjustable for height to come very slightly above the layer of mineral, a neutral gas being introduced between the vault and the dampers at a pressure slightly higher than that obtaining in the adjacent zones, and in the portion located underneath the cars the installation comprising a hollow box furnished with holes in its upper face and kept bearing against the lower faces of the cars, the box being fed with neutral gas at a pressure slightly higher than that obtaining in the adjacent zones.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,907,262 DATED September 23, 1975 Edouard BOIHIaUI'B it is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[30] "Feb. 17, 1972" should read --May 17, 1972--.

. Signed and Scaled this sixth D of January 1976 [SEAL] Attest:

RUTH c. MASON c. MARSHALL DANN Arresting Officer Commissioner nfParenrs and Trademarks 

1. An installation for the hot gaseous-flow treatment of pelletized minerals, employing a circular continuous grate formed by a series of cars and mechanisms for driving the cars and comprising a charging zone, at least one treatment station in each of which the grate passes between fixed gastight hoods, one upper and one lower, a discharge zone and neutral zones and cooling zones, the frames of the cars including water cooling circuit means and lateral gastight sealing means between the movable cars and the fixed upper and lower hoods, said sealing means including water seals arranged outside the gas flow path, the cars carrying blades which move with them and dip into fixed troughs filled with water and closed at their ends by flexible lips enabling the car blades to pass through, the cars and their grate-supporting cross-beams being clad with an inert insulating refractory layer and means for providing gastight sealing between two successive cars before approach to the charging station.
 2. An installation for treatment as in claim 1, wherein said means for transverse gastight sealing include projection of a plastic refractory cement into the space transversely separating two successive cars.
 3. An installation for treatment as in claim 1, wherein said means for transverse gastight sealing include a metalloplastic cord in the space transversely separating two successive cars.
 4. An installation for treatment as in claim 1, comprising neutral zones between different active zones, in each neutral zone and in the portion located above the cars the vault being lowered and closed at each end of the zone by a transverse damper adjustable for height to come very slightly above the layer of mineral, a neutral gas being introduced between the vault and the dampers at a pressure slightly higher than that obtaining in the adjacent zones, and in the portion located underneath the cars the installation comprising a hollow box furnished with holes in its upper face and kept bearing against the lower faces of the cars, the box being fed with neutral gas at a pressure slightly higher than that obtaining in the adjacent zones. 